The overall objectives of this research are to purify and to characterize the (Ca2 ion plus Mg2 ion ATPase from the human erythrocyte plasma membrane. A major objective for next year is adapting the technology for isoelectric focusing of membrane proteins to a larger preparative column. In this way we should be able to dramatically increase the quantity of protein purified while at the same time increase the resolution of the various protein species into more discrete units. In parallel with this adaptation, we will resume protein reconstitution studies in order to more accurately determine the membrane-related requirements or both activity of the enzyme and transport of Ca2 ion. A third objective will be to examine certain abnormal systems, such as red cell from patients with sickle cell anemia of hereditary spherocytosis to determine if the (Ca2 ion plus Mg2 ion ATPase itself, its activity or its membrane related requirements has changed.